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Thread: Exterior Door Flat Panel Construction

  1. #1

    Exterior Door Flat Panel Construction

    I am building a white oak exterior Dutch door (36x80) that will have flat modern panels instead of raised panels. I’m in Southern California and the door is west facing with some cover but mostly exposed in the late afternoon and I’m a couple miles from the coast. From reading (too much, now I’m confused and overthinking), I have picked up on some modern “engineered” door construction style. I have laminated the stiles and rails dead flat and am now focused on the panels. I have read on a few threads that it is common to have separate back-to-back raised panels to combat the temperature difference from inside to outside. I get that the tendency to split from thermal expansion is higher on a 1.75” thick panel, but if my flat panel ends up being only 7/8”-1” thick, is it still necessary to have two floating panels, each 1/2” thick, or is that overkill and a single panel is sufficient? Should I still make two 1/2” panels, but epoxy them together? Plywood with 1/8” shop sawn veneer? Veneer is my least favorite option as my bandsaw isn’t fully set up to resaw yet and I already have the lumber to build either 1” panel or two 1/2” panels.

  2. #2
    Kevin, I agree. Back to back panels are for panels that need to be flush with door frame or even thicker ( often called “off-set panels”).
    For your door one solid piece of oak will be fine.

  3. #3
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    Yes, I'd use a single panel. Just make sure to finish it completely before installation and that it can float in the frame.

    John

  4. #4
    Thanks John and Mel for your feedback, I’m now comfortable proceeding with a single panel, and will pre-finish the panel before assembly.

    Cheers!
    -Kevin

  5. #5
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    I think the biggest problem your going to encounter will be water intrusion at the bottom of the flat panels. I have for quite awhile felt that west facing door are subjected to the most severe conditions. If water does get into the bottom groove the end grain of the panel will suck up the water(I don't care how sealed) the MC will change and the panel may develop end checks, crack the finish and that's the beginning of the end. Coming from a marine background all the doors I've made have be laminated panels either flat or raised, Flat are easier. a center core of marine ply glued to desired thickness and faced with 1/8 veneer have served me well. Epoxy is used throughout as Titebond 3 will develop problems in the direct sunlight if there is heat build up and epoxy allows greater assembly time due to varied setting times available. The veneered pane can the be cut to fit exactly into its groove and may be also glued in place.
    If your planning on a bright exterior finish I would recommend using Epifanes marine finishes five coats minimum. If the exterior is opaque then any good topside paint will work, or Fine Paints of Europe, as long as its oil based, latex by nature is to porous. The interior should be give a finish as close to thickness a the exterior (bright or opaque)
    If the door is to be covered by a storm door, provide a venting screen top and bottom to allow excess heat to vacated the cavity between it and the door. This will greatly extend the exterior finish.
    If you elect to use solid panels I would strongly suggest coating the panels, particularly the end grain, use a thinned epoxy (50%) really soak the the ends. White oak is diffuse porous and take a while to wick up finish.

    I'll stop here. Door such as these require so much work to complete and over the years I have weeded out what has either failed or caused problems. I must admit that since using laminated panels , installed as above, I have had no failures.
    Good luck and let me know how you make out.

    Ed

  6. #6
    I saw a forest laboratory report recently where they tested a lot of finishes to see how they blocked moisture pickup. I think it was posted on another website but it might have been here. Epoxy was one of very few finishes that blocked moisture absorption pretty well. They were exposing test pieces to 90% humidity for weeks - more severe than the real world. But I think Ed's comments about using epoxy for the panels has a lot of merit based upon these test results. Solvent based paints also protected better than latex.

  7. #7
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    I treat the ends of panels with epoxy to help seal the end grain, but I also install weep holes to let water drain out. Water is going to find it's way between the panel and lower rail with an exposed door. Providing a means for the water to escape is as important as sealing the end grain, IMO.

    As for which finish is best on a wood door, the jury is out. I've used Cetol Door and Window finish with excellent results. One of it's selling points is that it's microporous and doesn't trap water underneath, which leads to blistering/failure of film finishes.

    John

  8. #8
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    I remember that cypress and white oak are excellent wood for exterior doors. If you buy one at a lumber yard, it will probably be fir.

  9. #9
    Quote Originally Posted by ed morini View Post
    I think the biggest problem your going to encounter will be water intrusion at the bottom of the flat panels. I have for quite awhile felt that west facing door are subjected to the most severe conditions. If water does get into the bottom groove the end grain of the panel will suck up the water(I don't care how sealed) the MC will change and the panel may develop end checks, crack the finish and that's the beginning of the end. Coming from a marine background all the doors I've made have be laminated panels either flat or raised, Flat are easier. a center core of marine ply glued to desired thickness and faced with 1/8 veneer have served me well. Epoxy is used throughout as Titebond 3 will develop problems in the direct sunlight if there is heat build up and epoxy allows greater assembly time due to varied setting times available. The veneered pane can the be cut to fit exactly into its groove and may be also glued in place.
    If your planning on a bright exterior finish I would recommend using Epifanes marine finishes five coats minimum. If the exterior is opaque then any good topside paint will work, or Fine Paints of Europe, as long as its oil based, latex by nature is to porous. The interior should be give a finish as close to thickness a the exterior (bright or opaque)
    If the door is to be covered by a storm door, provide a venting screen top and bottom to allow excess heat to vacated the cavity between it and the door. This will greatly extend the exterior finish.
    If you elect to use solid panels I would strongly suggest coating the panels, particularly the end grain, use a thinned epoxy (50%) really soak the the ends. White oak is diffuse porous and take a while to wick up finish.

    I'll stop here. Door such as these require so much work to complete and over the years I have weeded out what has either failed or caused problems. I must admit that since using laminated panels , installed as above, I have had no failures.
    Good luck and let me know how you make out.

    Ed
    Ed, Thanks for the detailed response. Took me a bit to see it, I didn't get any notifications. I am using epoxy instead of TB3 as you suggest. There won't be a storm door - I live in Southern California, what's a storm? I like the idea of epoxying the end grain on the panels, and will incorporate that.

    As for the finish, I am leaning towards the Epifanes you recommend, but my wife really does not want a glossy finish. I'm not sure if there is another option with a softer look that will work as well, or at least allow for easy maintenance as needed? Or is my best bet to just use the Epifanes matte finish for the final coat?

  10. #10
    Quote Originally Posted by John TenEyck View Post
    I treat the ends of panels with epoxy to help seal the end grain, but I also install weep holes to let water drain out. Water is going to find it's way between the panel and lower rail with an exposed door. Providing a means for the water to escape is as important as sealing the end grain, IMO.

    As for which finish is best on a wood door, the jury is out. I've used Cetol Door and Window finish with excellent results. One of it's selling points is that it's microporous and doesn't trap water underneath, which leads to blistering/failure of film finishes.

    John
    John, I had been thinking of weep holes but am not sure of how that detail looks on a wood door. Do you still have the weep hole facing the exterior like on a window frame? How large does it need to be to allow water to drain but remain inconspicuous?

  11. #11
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    Quote Originally Posted by Kevin Crider View Post
    Ed, Thanks for the detailed response. Took me a bit to see it, I didn't get any notifications. I am using epoxy instead of TB3 as you suggest. There won't be a storm door - I live in Southern California, what's a storm? I like the idea of epoxying the end grain on the panels, and will incorporate that.

    As for the finish, I am leaning towards the Epifanes you recommend, but my wife really does not want a glossy finish. I'm not sure if there is another option with a softer look that will work as well, or at least allow for easy maintenance as needed? Or is my best bet to just use the Epifanes matte finish for the final coat?
    Epifanes is good stuff but it's not easy maintenance. Heck, it's not even easy to apply the first time - seven coats. I've had great luck with Cetol Door and Window finish. It only takes 2 or 3 coats and there is a satin clear coat you can apply as the last coat for a satin finish. Goes on great with a bristle brush - looks sprayed.

    John

  12. #12
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    Quote Originally Posted by Kevin Crider View Post
    John, I had been thinking of weep holes but am not sure of how that detail looks on a wood door. Do you still have the weep hole facing the exterior like on a window frame? How large does it need to be to allow water to drain but remain inconspicuous?
    Keven, I used weep holes on this West facing door:



    They are hidden in the reveal of the molding at the bottom of the panels:



    The panels are removable from the inside and I will clean out the weep holes, if needed, when I refresh the finish on the door later this Summer. The finish is Cetol Door and Window finish, two coats of Mahogany on the raw Sapele, followed by one coat of clear satin. Four years and it now needs to be refreshed. No cracks or peeling, it's just faded. My plan is to clean it, scuff sand it with 400 or 600 grit, then apply one or two coats of mahogany followed by a coat of satin. I'll finish the panels separately, just as I did when I built it, so they don't bond to the frame and are free to expand/contract. FWIW, these panels are two piece, 3/4" each, so the inside and outside pieces can respond independently.

    John

  13. #13
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    Epifanes does make a matte finish that will accentuate the wood grain rather than the shine. I’ve used most of the Cetol products and they certainly have their well deserved place. I find them a more hand applied type finish allowing for rag type application( my opinion only). Very similar to Waterlox another great marine finish.
    The varnish give a much higher build and being a varnish and somewhat harder ( tougher) film. The marine (spar) vanishes
    in addition to phenolics or alkyd bases have a fair amount UV inhibitors. These have a long and successful history in the better known brands.
    As far as the the coating schedule, that’s a one time process. It allows a very substantial base to be laid down and allows for sanding after the outer surface has been exposed to the elements. Ideally a once a year chore. I suspect you might get 3 years facing west, I’m up to seven facing north, with a vented storm door using a shielding glass.
    One thing that is certain, no matter which type finish you decide to use there will be some sort maintenance to prevent the inevitable water intrusion

    Ed

  14. #14
    Ed and John,

    Just wanted to come back to say thank you for your advice on construction and finish. It took forever for a mediocre finisher like myself to get a quality finish with the Epifanes but I finally just installed the door a couple weeks ago and I’m very pleased with the results!
    99F6B196-736F-41DA-BC95-F8C0EEAFE58D.jpg
    Thanks,

    -Kevin

  15. #15
    Quote Originally Posted by John TenEyck View Post
    Keven, I used weep holes on this West facing door:



    They are hidden in the reveal of the molding at the bottom of the panels:



    The panels are removable from the inside and I will clean out the weep holes, if needed, when I refresh the finish on the door later this Summer. The finish is Cetol Door and Window finish, two coats of Mahogany on the raw Sapele, followed by one coat of clear satin. Four years and it now needs to be refreshed. No cracks or peeling, it's just faded. My plan is to clean it, scuff sand it with 400 or 600 grit, then apply one or two coats of mahogany followed by a coat of satin. I'll finish the panels separately, just as I did when I built it, so they don't bond to the frame and are free to expand/contract. FWIW, these panels are two piece, 3/4" each, so the inside and outside pieces can respond independently.

    John

    Lovely door John and thank for the details on the weep holes.

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